Optical element and illumination optics for microlithography
View Patent ↗The disclosure relates to an optical element and illumination optics for microlithography. The optical element can be configured to influence a nominal beam angle, preset over a beam cross-section, of a radiation beam hitting the optical element. Moreover, the disclosure relates to an illumination optics for the microlithography with at least one such optical element and an illumination system for the microlithography with such an illumination optics.
1. An optical element, comprising:
a spatial optical structure configured to influence a nominal beam angle of a radiation beam when the spatial optical structure is exposed to the radiation beam; and
an optical coating supported by the spatial optical structure, the optical coating being configured to generate a defined attenuation of parts of the radiation beam over a beam cross-section when exposed to the radiation beam, thereby influencing the nominal beam angle of the radiation beam,
wherein optical effects of the spatial optical structure and the optical coating complement each other in influencing the nominal beam angle of the radiation beam, and
wherein the optical coating is designed so that beam angles generated by the spatial optical structure that exceed a divergence angle limit are absorbed or reflected by the optical coating.
2. The optical element according to claim 1 , wherein the spatial optical structure has a diffractive effect on the radiation beam.
3. The optical element according to claim 1 , wherein the spatial optical structure has a refractive effect on the radiation beam.
4. The optical element according to claim 1 , wherein the optical coating is an interference coating.
5. The optical element according to claim 1 , wherein the spatial optical structure comprises a plurality of raster elements.
6. The optical element according to claim 5 , wherein:
the optical coating is configured to cause a maximum attenuation of the radiation beam at a first point of incidence on one of the raster elements and a minimum attenuation of the incident radiation beam at a second point of incidence on the same raster element; and
a difference in attenuation between adjacent raster elements is less than a difference between the maximum and minimum attenuation.
7. The optical element according to claim 1 , wherein the optical coating is designed to generate an attenuation to correct the influence on the beam angle exerted by the spatial optical structure.
8. The optical element according to claim 1 , wherein:
the spatial optical structure is designed to generate a far field distribution for the incident radiation beam;
a first intensity is generated at a first position of the far field;
a second intensity is generated at a second position of the far field;
the first and second intensities differ by at least 5%; and
the optical effect of the optical coating and the optical effect of the spatial optical structure complement each other so that the total far field distribution generated by the optical element is constant in at least a portion comprising the first and second positions.
9. An optical system, comprising:
an optical element according to claim 1 ,
wherein the optical system is a microlithography illumination optics.
10. The optical system of claim 9 , wherein the optical element is configured to set an angular distribution of an intensity of illumination light in a reticle plane.
11. The optical element of claim 9 , wherein the optical element is configured to set a field distribution of an intensity of an illumination light in a reticle plane.
12. An optical system, comprising:
a light source; and
an illumination optics comprising the optical element of claim 1 ,
wherein the optical system is microlithography illumination system.
13. The optical system of claim 12 , wherein the optical element is configured to set an angular distribution of an intensity of illumination light in a reticle plane.
14. The optical element of claim 12 , wherein the optical element is configured to set a field distribution of an intensity of an illumination light in a reticle plane.
15. An optical system, comprising:
an optical element of claim 1 ,
wherein the optical system is a microlithography projection exposure apparatus.
16. The optical system of claim 15 , comprising an illumination optics comprising the optical element.
17. The optical system of claim 16 , comprising an illumination system comprising the illumination optics.
18. The optical system of claim 17 , further comprising a projection objective.
19. An optical element, comprising:
a spatial optical structure configured to influence a nominal beam angle of a radiation beam when the spatial optical structure is exposed to the radiation beam; and
an optical coating supported by the spatial optical structure, the optical coating being configured to generate a defined attenuation of parts of the radiation beam over a beam cross-section when exposed to the radiation beam, thereby influencing the nominal beam angle of the radiation beam,
wherein optical effects of the spatial optical structure and the optical coating complement each other in influencing the nominal beam angle of the radiation beam, and
wherein the optical coating is designed so that beam angles generated by the spatial optical structure that are below a divergence angle limit are reflected by the optical coating.